[FFmpeg-user] (de)-interlacing question

[Toerless Eckert]

On Tue, Nov 22, 2016 at 12:18:43PM +0000, Andy Furniss wrote:
> Seems strange that that would happen. It certainly doesn't in the UK,
> 25fps progressive SD does get flagged as interlaced

Any idea why that flag is set ? Just because it makes the programming
look more compatible ? Is there really any equipment that could not
display the content without the flag or create a worse display result
if it was not set ? Seems to me that even if you connected a digital STB
to a CRT, every digitial STB would still be able to display a non-interlaced
flagged program with the same visual result.

> but there is no
> interpolation. Have you tried frame stepping with say mplayer - it could
> be that vlc is adding filters because of the flags.

Whow, thats a far out idea ;-) WOuld love to challenge you: Vlc uses
ffmpeg to do the hard parts. And i'd be quite curious if ffmpeg could
create motion interpolated frames. Any example CLI line to do that ? 

Btw: mplayer single steps displays frames. The MPEG2 SD TS recording
shows clearly interlaced frames. The H264 MPEG4 HD mediathek file shows
every second frame to be identical. Vlc seems to step fields, so i
see non-interlaced field by field for the MPEG2 SD TS recording. And same
frame duplication for the HD.

> Also noted you say "Just download" which makes me wonder whether you are
> talking about web content rather that broadcast.

Yes indeed. I had only recorded (MPEG2 TS) of a program and then downloaded
later the H264 HD version from mediathek to compare. I'll record
another program HD and SD to make sure that the mediathek HD file didn't
strip actual p50 programming into p25. Of course this is still no 100%
proof, the production mater could still have been p50 and they use more
spatial bits for their HD channels and more temporal ones for the SD version.

Which is why i'd like to see how good motion interpolation created by eg: ffmpeg
could be to see if one can recognize it (being worse than actual frames).

btw: there where reports saying that TV productions ARD/ZDF are p25 and only
sports is actual p50. Eg: 

http://www.heise.de/newsticker/meldung/Petition-gegen-720p-HD-bei-ARD-und-ZDF-941806.html

Cheers
    Toerless